Last week a student asked me to explain what "glazing" is. I didn't give a very definitive answer for him, so I decided to do some research on the subject and I have since learned that glazing is a process of applying a thin, transparent layer of paint on top of an underpainting (monochromatic grisaille) or a painting (with color) that is dry. The layers are not to be physically mixed, but are optically mixed. It is important to note that the paint color (out of the tube) should be transparent. The transparent paint allows light to pass through to the layer beneath. The transparent paint glaze appears luminous and bright, making colors look rich. For example, when I painted with watercolors I applied many, many layers of transparent paint starting with a bright white paper. I applied these layers until I achieved the result I wanted, which was the illusion of form, light, color and value. (I painted with watercolor for about 18 years and never really knew that what I was doing was called "glazing".) By the way, most oil painters, from the advent of oil painting, practiced the process of first painting an underpainting, layers of color, and glazes. Johannes Vermeer used glazes when he painted many of his paintings. Girl With The Pearl Earring, by Johannes Vermeer, was painted using glazes.